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SubjectRe: [PATCH v1 2/2] scsi: ufs: Support reading UFS's Vcc voltage from device tree
On Tue 01 Sep 01:00 CDT 2020, Bao D. Nguyen wrote:

> The UFS specifications supports a range of Vcc operating voltage
> from 2.4-3.6V depending on the device and manufacturers.
> Allows selecting the UFS Vcc voltage level by setting the
> UFS's entry vcc-voltage-level in the device tree. If UFS's
> vcc-voltage-level setting is not found in the device tree,
> use default values provided by the driver.
>

As stated in the reply to patch 1, this is not the right approach. As
long as you have static min/max values requested by the driver you
should rely on the board's constraints for the regulator levels and
instead remove the min_uV/max_uV code from the driver.

Thanks,
Bjorn

> Signed-off-by: Can Guo <cang@codeaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
> Signed-off-by: Bao D. Nguyen <nguyenb@codeaurora.org>
> ---
> drivers/scsi/ufs/ufshcd-pltfrm.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
> index 3db0af6..48f429c 100644
> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
> @@ -104,10 +104,11 @@ static int ufshcd_parse_clock_info(struct ufs_hba *hba)
> static int ufshcd_populate_vreg(struct device *dev, const char *name,
> struct ufs_vreg **out_vreg)
> {
> - int ret = 0;
> + int len, ret = 0;
> char prop_name[MAX_PROP_SIZE];
> struct ufs_vreg *vreg = NULL;
> struct device_node *np = dev->of_node;
> + const __be32 *prop;
>
> if (!np) {
> dev_err(dev, "%s: non DT initialization\n", __func__);
> @@ -138,8 +139,16 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
> vreg->min_uV = UFS_VREG_VCC_1P8_MIN_UV;
> vreg->max_uV = UFS_VREG_VCC_1P8_MAX_UV;
> } else {
> - vreg->min_uV = UFS_VREG_VCC_MIN_UV;
> - vreg->max_uV = UFS_VREG_VCC_MAX_UV;
> + prop = of_get_property(np, "vcc-voltage-level", &len);
> + if (!prop || (len != (2 * sizeof(__be32)))) {
> + dev_warn(dev, "%s vcc-voltage-level property.\n",
> + prop ? "invalid format" : "no");
> + vreg->min_uV = UFS_VREG_VCC_MIN_UV;
> + vreg->max_uV = UFS_VREG_VCC_MAX_UV;
> + } else {
> + vreg->min_uV = be32_to_cpup(&prop[0]);
> + vreg->max_uV = be32_to_cpup(&prop[1]);
> + }
> }
> } else if (!strcmp(name, "vccq")) {
> vreg->min_uV = UFS_VREG_VCCQ_MIN_UV;
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

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